/* 
 *
 * The MIT License (MIT)
 * 
 * Copyright (c) 2015 Charles Salvia
 * 
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 * 
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 *
*/

#ifndef INCLUDE_STACK_ALLOCATOR_HPP
#define INCLUDE_STACK_ALLOCATOR_HPP

#include <functional>
#include <memory>
#include <iostream>

template <class T, class Allocator = std::allocator<T>>
class stack_allocator
{
  public:

  typedef typename std::allocator_traits<Allocator>::value_type value_type;
  typedef typename std::allocator_traits<Allocator>::pointer pointer;
  typedef typename std::allocator_traits<Allocator>::const_pointer const_pointer;
  typedef typename Allocator::reference reference;
  typedef typename Allocator::const_reference const_reference;
  typedef typename std::allocator_traits<Allocator>::size_type size_type;
  typedef typename std::allocator_traits<Allocator>::difference_type difference_type;

  typedef typename std::allocator_traits<Allocator>::const_void_pointer const_void_pointer;
  typedef Allocator allocator_type;
  
  public:

  explicit stack_allocator(const allocator_type& alloc = allocator_type()) 
    : m_allocator(alloc), m_begin(nullptr), m_end(nullptr), m_stack_pointer(nullptr)
  { }

  explicit stack_allocator(pointer buffer, size_type size, const allocator_type& alloc = allocator_type())
    : m_allocator(alloc), m_begin(buffer), m_end(buffer + size), 
      m_stack_pointer(buffer)
  { }

  template <class U>
  stack_allocator(const stack_allocator<U, Allocator>& other)
    : m_allocator(other.m_allocator), m_begin(other.m_begin), m_end(other.m_end),
      m_stack_pointer(other.m_stack_pointer)
  { }

  constexpr static size_type capacity()
  {
    return N;
  }

  pointer allocate(size_type n, const_void_pointer hint = const_void_pointer())
  {
    if (n <= size_type(std::distance(m_stack_pointer, m_end)))
    {
      pointer result = m_stack_pointer;
      m_stack_pointer += n;
      return result;
    }

    return m_allocator.allocate(n, hint);
  }

  void deallocate(pointer p, size_type n)
  {
    if (pointer_to_internal_buffer(p))
    {
      m_stack_pointer -= n;
    }
    else m_allocator.deallocate(p, n);  
  }

  size_type max_size() const noexcept
  {
    return m_allocator.max_size();
  }

  template <class U, class... Args>
  void construct(U* p, Args&&... args)
  {
    m_allocator.construct(p, std::forward<Args>(args)...);
  }

  template <class U>
  void destroy(U* p)
  {
    m_allocator.destroy(p);
  }

  pointer address(reference x) const noexcept
  {
    if (pointer_to_internal_buffer(std::addressof(x)))
    {
      return std::addressof(x);
    }

    return m_allocator.address(x);
  }
  
  const_pointer address(const_reference x) const noexcept
  {
    if (pointer_to_internal_buffer(std::addressof(x)))
    {
      return std::addressof(x);
    }

    return m_allocator.address(x);
  }

  template <class U>
  struct rebind { typedef stack_allocator<U, allocator_type> other; };

  pointer buffer() const noexcept
  {
    return m_begin;
  }

  private:

  bool pointer_to_internal_buffer(const_pointer p) const
  {
    return (!(std::less<const_pointer>()(p, m_begin)) && (std::less<const_pointer>()(p, m_end)));
  }

  allocator_type m_allocator;
  pointer m_begin;
  pointer m_end;
  pointer m_stack_pointer;
};

template <class T1, class Allocator, class T2>
bool operator == (const stack_allocator<T1, Allocator>& lhs, 
  const stack_allocator<T2, Allocator>& rhs) noexcept
{
  return lhs.buffer() == rhs.buffer();
}

template <class T1, class Allocator, class T2>
bool operator != (const stack_allocator<T1, Allocator>& lhs, 
  const stack_allocator<T2, Allocator>& rhs) noexcept
{
  return !(lhs == rhs);
}

// -------- Specialization for void
//
template <class Allocator>
class stack_allocator<void, Allocator>
{
  public:

  typedef std::size_t size_type;
  typedef std::ptrdiff_t difference_type;
  typedef void* pointer;
  typedef const void* const_pointer;
  typedef void value_type;

  constexpr pointer buffer() const noexcept
  {
    return nullptr;
  }

  template <class U>
  struct rebind
  {
    typedef stack_allocator<U, typename Allocator::template rebind<U>::other> other;
  };
};

#endif
